A body kit is a packaged set of aftermarket body parts to install on a stock vehicle to alter the appearance or to improve performance. Using body kits can enhance your vehicle’s performance aerodynamically by increasing downforce and minimizing drag, through engine performance by cooling or to make more room for component modifications like wider fenders for wider tires.
Splitters are installed at the front of the car that is attached to the bottom of the bumper and is an edge that sticks out to try to keep the pressure on top of the car instead of going under the car. It builds up high air pressure around the bumper causing it to migrate around the car. Some modifiers combine splitters with a front air dam to direct the air into productive areas such as for brake or radiator cooling. While attempting to keep the air out, it can also act with the high pressure to create downforce at the front end of the car. They are usually supported with rods that keep its angle parallel to the ground. Side skirts are a bit similar to splitters but only prevent high-pressure air from entering underneath the vehicle.
Dive planes or canards are fixtures that are located on the left and right sides of the front bumper. They are small triangle wings that are curved and when installed, create some downforce by redirecting the air upwards. Since this is only a small amount of downforce, canards are usually used for trimming purposes to fine-tune the vehicle's handling. Canards can also be installed with a vortex generator which is another triangle but is smaller and is installed a few centimeters above the canard to generate strong vortices that travel along the side of the car to act as a barrier. If they are positioned correctly they can prevent high-pressure air from entering the underbody and in doing so, create more downforce.
Ventilated hoods allow for increased cooling. They can either bring in more air under the hood or let air escape. A hood scoop can allow more air for cooling such as a top mount intercooler or for an engine inlet like an air filter. Using a hood scoop without enough ventilation from the underside will cause increased pressure at the hood scoop which is called spillover and will create drag. A hood vent allows for a clean exit for air passing through the radiator and allows for airflow through the engine bay. This is especially useful in a racecar where it has a full undertray and the air cannot ventilate underneath.
NACA ducts are scoops that are designed to intake airflow while minimizing the disturbance of air flow and drag. They can be used in almost any application that needs air such as an air intake or cooling where the engine components are not directly exposed to airflow. They can be placed anywhere such as the roof or side body panels.Side vents are the opposite of NACA ducts and can be used for airflow to exit like a hood vent. They can usually be seen behind the wheels where the turbulent from the wheel rotation remains.
Underbellies and diffusers are body mods for underneath the car. Underbellies are often smooth and flat to minimize drag and to reduce turbulence under the vehicle. A diffuser is a portion of the underbody that is shaped to create a larger air volume at the rear of the car that allows low-pressure air that is moving fast under the entire car to decrease in velocity and expand at the end. It helps increase the velocity of the air under the car while reducing its pressure, thereby increasing downforce.
Spoilers are used to decrease lift by placing a barrier in the way of lift-creating airflow at high speeds. They are not to be confused with rear wings as their main purpose is to not create downforce. Spoilers create a pocket of air between the rear window and spoiler causing the main airstream flow to go around the pocket of air and not have much contact with the actual spoiler.
Wings cause downforce that allows better rear wheel grip and lets the car achieve higher speeds at corners. They are designed to directly deflect air flow upwards as it pushes down on the vehicle. This creates drag and decreases the top speed of the vehicle.